Introduction
Literature review entails texts authored by a writer or research to evaluate the critical aspects of a given subject. In this literature review, we consider the ecology of American black bear. Scientifically, black bear is called Ursus americanus. The species belongs to the Family Ursidae. Family Ursidae is separated into a number of other sub-family groups. The giant panda and the spectacled bear fit in a unique sub-family. They are the least meticulously connected to the black bear. The brown, Asiatic and Polar bears are meticulously connected to the black bear. The black bear is not necessarily black. The colors range from cinnamon chocolate and grey-azure. Occasionally, the black bears are white in color. In essence, the white bears are known as Kermode bears.
Main Body
Geographical distribution
American black bears are prevalent in North America. They are not found in any other continent. Historically, the black bear was spread across all the forested parts of eastern North America. This includes the Appalachian Mountains. During the 20th century, unregulated hunting and loss of habitat led to the complete wiping out throughout most of the eastern North America (Laliaberte & Ripple 2004). Although the black bear continues to be absent in parts of the historically-occupied environment, the populations have been observed to be on the rise. In the last few decades, the species have been reoccupying a number of states. Black bears are adaptive in nature. The distribution of the black bears in the entire continent centuries ago demonstrates this fact. They occupied 49 of the 50 states (Tredick & Vaughan 2009).
Hawaii was the only exemption. The species also occupied all the ten Canadian provinces. Modernly, they no longer live in Prince Edward Island. Additionally, they are completely wiped out or almost so in about fifteen states they originally occupied in the United States (Sayler 2006).
Pattern of distribution
Notwithstanding that the number of black bears has been increasing in the last few decades, some states are not inhabited by a single black bear. This is largely due to diminishing habitat arising from human activity. It has been observed that the extinction of the black bear in these states is not necessarily due to poaching. The bears migrate involuntarily to other states according to the American Bear Association (1993). The table below indicates the states which the black bears initially occupied in large numbers.
How individuals are distributed
The determination of the number of black bears in a specific region is a challenging task according to American Bear Association (1993). The association associates the difficult to the nature of black bears. Bears are difficult to find considering their shyness and elusiveness. Furthermore, bears may wander extensive distances during summer while looking for food. Inherently, the ephemeral behavior transfers the bears transversely across geographical borders. The phenomenon makes it difficult for agencies to attain a precise approximation of the bear numbers. According to Gary Brown (1993), it is supposed that the number of black bears at the arrival of European settlers was more than half a million bears wandering the continent. Contemporarily, the number has increased irrespective of the fact that the bears have lost a substantial tract of their historic habitat. Estimates indicate that there were about 725,000 black bears across the continent by the year 1993. Given the high rate of reproduction of the species, there may be more than a million black bears wandering the continent.
Major habitats
Black bears live in forests, wetlands and tundra across the eastern and northerly areas of North America. In other regions such as the Pacific Northwest, the bears inhabit the edges of towns and urban outskirts. In areas where the bears live near people, they are known to break into stores and cars when searching food. These areas have lesser natural foods for the bears resulting in the queer behavior. This indicates that black bears are adjustable to a variety of habitations but are more inclined towards forests (Klappenbach 2014). In areas such as Florida, black bears occupation range has been decreased to six main areas. They can be found in any part of Florida. However, they prefer a combination of low woods, undergrowth oak edges, cove heads and hammock areas. The area where the black bears inhabit due to adequate supply of food, water and hiding place is referred to as ‘home range’.
Habitat components
Typically, black bears are intimidated by humans. They hence prefer living in natural settings such as forests and swamps where human activity is limited. In their natural settings, the black bears inhabit areas with adequate supply of berries. They are good tree climbers with powerful claws. The feature enables the black bears to survive in areas where logs are available for insects to thrive. Additionally, there must be sufficient supply of leaves to supplement the diet. Black bears are known to rip beehives apart and consume the larvae and the honey. The areas that black bears voluntarily inhabit due to adequate supply of all the essentials can be easily identified. These ‘home ranges’ comprises of a central bear population. The movement of the bears when clandestinely observed is free. Additionally, there is indication of reproduction underscored by the presence of dens (Frary et al. 2011).
Bearing in mind that black bears are forest dwellers, they may be found in large numbers in deciduous, coniferous or mixed forests. They are found in these forests from between sea-level and ten thousand feet above sea level. The home ranges are characterized by dense undergrowth. The forest is identifiable by plentiful availability of fruit and nut-yielding trees.
Foods eaten
Typically, black bears mostly feed on berries as the favorite food. They augment the diet with nuts, grass and meat. They also include insects for protein supply in shortage of meat. The black bears have also been observed to nibble herbs when they are not too hungry to look for larger food supplies. They climb trees with ease in search of berries and favorite leaves. They are good swimmers and occasionally eat fish.
Timing and pattern of production
Black bears are not actual hibernators. They experience what is referred to as ‘winter lethargy’. This is a period when the bears have the least activity. The period arises due to a variety of factors. These include reproductive status, accessibility of food and temperature variations. The breeding period lasts between June and July. They have a distinct breeding version referred to as ‘delayed implantation’. The ovum is fertilized during summer.
However, it is not implanted in the uterine walls immediately. It stays in the fallopian tube until November. The health condition of the mother determines whether or not the fertilized egg will be implanted. Poor health leads to reabsorption of the egg or miscarriage occurs. A healthy female black bear often deliver a larger brood. The interrupted food availability due to winter ensures that the bear does not produce more cubs than she can feed. The gestation period for black bears is 8 to 12 weeks. The cubs are tiny at birth compared to the size of a mature bare. They weigh between 220 to 450 grams. This is as small as a squirrel.
Pregnant black bears hibernate for the whole winter. The cubs require being born in a den. Consequently, the females choose highly protected areas whenever possible. These include thick bushes, tree hollows or fallen woods according to Florida Fish and Wildlife conservation Commission (2014). The cubs are born with a smooth hairy coat. A healthy female may deliver up to four cubs. They stay in the lair until spring. They are under the protection of the mother for one and a half years. In the second summer after birth, the youngsters stroll. The mother is ready to breed again. The young males are required to move away from the mother’s neighborhood. The young females may establish a territory within or intersecting the mother’s.
Home range
Depending on place, period, food accessibility, the number of bears in an area, the gender and age of the bear, the home range varies. Typically, the home range of a male is wider compared to a female bear. Every male’s home range often intersects that of several other females. When the area has poor supply of the bears’ essentials, the home range has to be increased for the bear to get enough of the supplies. These include water and food.
Conservation
Research indicates that the number of black bears has been increasing. They are gradually reoccupying several states that they had become extinct (Pelton et al 1998). The authors indicate that the peculiar increase pattern of the species contradicts the generalized pattern of decline among the world’s seven other bear species. The recolonizing of remarkable range by the black species demonstrates enhanced resource management. It also reflects growing tolerance among people in these areas. However, the reclamation of any large omnivore institutes the probability of human/wildlife contact and conflict (MacKenzie 2006).
Conserving bears is not always challenging. Black bears are not particularly territorial. However, research indicates that some females can be overly territorial. In such a case, intrusion is violently resisted. The resistance may even result in serious injuries. The smaller size of the female home range allows them to keenly observe the activities and the inhabitants. On the other hand, it is almost unimaginable for a male black bear to effectively protect a large home range measuring hundreds square miles. They instead forgo the aspect of territory but ensure supremacy hierarchy to maintain social order. They declare their presence through scent marking.
This includes biting trees and urinating. It has been observed that black bears assemble in places with sufficient food supplies without fighting. This makes it easier to create conservancies for the protection of the animal. Such areas include the Pacific Northwest where there is abundant salmon supply. Other places include garbage dump sites. Fights among black bears may flare up occasionally. However, need for food supersedes that inherent fear of one another (Royle & MacKenzie 2005).
Population management
The number of black bears in North America is overwhelming. The number continues to increase annually. The habitat is reducing rapidly due to human activity. There is high potential for conflict to arise between human, black bears and the wildlife in generally. Consequently, there is dire need for the population of the black bears to be managed. Although contentious, the use of contraceptives and sterilizing methods can be effective as substitutes for the contemporary methods of culling. Immuno-contraception may be an option for population management of black bear population (Paetkau 2003). The method utilizes body’s immune reaction to avert pregnancy. According to Bear Smart Society, it has previously been used on a variety of wildlife species including horses, deer and Ilamas. Similarly, it has been used to control black bear population in South Dakota (Liu 2014).
The advantage of this population management method is that it is non-invasive. The method is alleged to be effective especially when managing black bear population in suburbs and urban peripheries considering that female bears are aggressive when they are protecting cubs. The use of the immune-contraception method of managing bear population therefore reduces human/bear conflict.
Conclusion
Although they are called black bears, colors may range from black to cinnamon chocolate, grey-azure and even white. They mainly depend on berries, nuts, pastures, meat, and creepy-crawly larvae. They are respectable tree climbers and swimmers. They are very intellectual and nosy. These are some of the aspects that need to be understood in managing black bear environments. It is also imperative to note that they can run up to 55 kilometers per hour. Notably, they can go without food for seven months during hibernation. They normally deliver 2 to 3 cubs every two years. They can live over 25 years in the wild. They are characteristically shy and certainly panicky making them dangerous.
References
Brown, G 1993, Population and distribution of the black bear. Web.
Frary, V et al 2011 ‘Density and distribution of a colonizing front of the American black bear Ursus americanus’, Wildlife Biology, vol. 17. no. 1, 404-416. Web.
Klappenbach, L 2014, American black bear. Web.
Laliaberte, A & Ripple, W 2004 ‘Range contractions of North American carnivores and ungulates’, BioScience, vol. 54. no. 2, 123-138. Web.
Liu, K 2014, Humane wildlife population control. Web.
MacKenzie, D 2006 ‘Modeling the probability of use: the effect of, and dealing with detecting a species imperfectly’, Journal of Wildlife Management, vol. 70. no. 2, 367-374. Web.
Paetkau, D 2003 ‘An empirical exploration of data quality in DNA-based population inventories’, Molecular Ecology, vol. 12. no. 6, 1375-1387. Web.
Royle, J & MacKenzie, D 2005 ‘Designing occupancy studies: general advice and allocating survey effort, Journal of Applied Ecology, vol. 42. no.6, 1105-1114. Web.
Sayler, K 2006, Contemporary land cover change in the central Appalachians Eco-region. Web.
Tredick, C & Vaughan, M 2009 ‘DNA-based population demographics of black bears in coastal North Carolina and Virginia’, Journal of Wildlife Management, vol. 73. no. 7, 1031-1039. Web.